Fuel injection control



Aug. 21, 1956 w. F. ISLEY 2,759,469

FUEL INJECTION CONTROL Filed July 27, 1953 INVENTOR.

WALTER F. ISLEY mvfwar ATTOFINEYS United States Patent ()flice 2,759,469 Patented Aug. 21, 1956,

FUEL INJECTION CONTROL Walter F. Isley, Grosse, Pointe, Mich., assignor to Continental Motors Corporation, Detroit, Mich., a corporation of Virginia Application July 27, 1953, Serial N'o., 370,535. 6 Claims. (Cl-,123-140) The present invention relates to fuel injection control means for the purpose of controlling the operation of fuel injection pumps and specifically to the actuation of such means in relation to manifold. pressures of fuel injection engines.

In the regulation of fuel delivery from variable discharge pumps in accordance with manifold pressures, the results heretofore obtained do not provide the fuel economy desired nor the most eflicient fuel-air ratios ob tainable at engine idling speeds.

If some compensation is not made for the idling condition, the fuel air ratios become excessively rich. At low engine speeds as exist at idling conditions, the air consumption characteristics of the engine are such that the air taken into a cylinder per cycle is considerably less than at higher speeds and similar manifold pressures. Since some fuel injection pumps deliver essentiallyconstant amounts of fuel per cycle at all speeds at a given control pressure, the fuel-air ratio becomes too rich at idling conditions for most eliicient operation.

No system of fuel injection control means heretoforeutilized provides for an independent idle fuel control by manually adjusting the injector control pressure at the idling throttle position, and then provide for a control pass-out range at throttle positions above idling so that the normal injection control will then prevail.

Therefore, an object of the present invention is to maintain an efficient fuel-air ratio. at engine idling speeds by providing a fuel injection control means with which adequate adjustment can be made to the fuel rate in response to simple manual adjustment independent of manifold pressures with the throttle at closed or near closed position.

Another object of the invention is to. maintain independence of the control at idling speeds. by providing a manifold pressure sensitive method of rendering the idling control means inoperative when the throttle is advanced, transferring control of fuel injection to other means.

Still another object of the invention is to simplify the fuel metering control by providing a valve: comprising a minimum of connections and adjusting means, and utilizing none of the mechanical linkages to the throttle Whichheretofore have proven unreliable, due, to complexity of structure and inadequate control.

With these and other objects in mind as will be. readily understood by those skilled in the art upon references. to the following specification and drawing wherein like characters refer to like parts throughout the views, and in which Fig. 1 is a diagrammatic illustration showing the arrangement and operation of the invention;

Fig. 2 is a cross section of control device outlined by the dotted lines designated A in Fig. I;

Fig. 3 is a section on line 33 of- Fig. 2; Fig. 4 is a section on line 4-4 of Fig. 2; and Fig. 5 is a, sectional view of a detail.

In the drawings, referring first. to Fig. 1, a supercharged.

engine (not shown). is, indicated with an air intake system,

comprising a supercharger 10, an air inlet 11 and an outlet 12 leading to the engine manifold. A suitable variable output fuel injectionpump is indicated at 13, the variation of output being controlled by thev position of a pin 13A determined by the pressure-responsive bellows 13B, the operation of Which is due to variations in pressure in the enclosing pressure compartment 13C. A decrease of pressure in compartment 13C results in a reduced fuel rate output of the pump 13.

From the diagram of Fig. 1, it will be noted that three conduits 14, 15 and 16 are open to the main air intake system, conduit 14 opening to inlet 11 close to but ahead of the throttle 17. The second conduit 15 is open to the intake system downstream of throttle 17 but upstream of the supercharger 10. The third conduit 16 isv open to the main air intake system downstream of the supercharger.

With the throttle in closed or idle position, atmospheric pressure will prevail in conduit 14, a pressure substantially less than atmospheric in the conduit 15 and apressure only a little below atmospheric in the conduit 16 due to the partial vacuum prevailing in the engine intake.

As indicated, the conduit 14 leads first to a check valve fixture 14A, beyond which it branches, one branch 14B terminating in the jet 14C of a venturi fixture 18. The other branch 14D leads through a bypass valve 19 to a conduit 20 and to the low pressure throat of the venturi 18.

The conduit 15 is also branched with one branch 15A leading to the outlet of a needle valve 21 enclosed in a casing 22 and fixed to a diaphragm 23 in the casing, while the other branch 15B leads to the casing 22 under the diaphragm, i. e. to the side of the latter opposite the needle valve 21.

The conduit 16 is arranged to receive the flow of air from the jet 14C and is also open to the low pressure throat of the venturi, to which is also connected the conduit 29.

This conduit 20 is, as stated above, open to the branch 14D, and is connected to both the pressure compartment 13C of the pump and to chamber 22, terminating in the latter on the needle valve side of the diaphragm 23. A suitable restriction 20A is placed in conduit 20 between venturi 1'8 and the connection to the pump.

Under the diaphragm 23 is a suitable spring 23A adapted to exert a pressure tending to close the needle valve 21, while a light spring 23B surrounds the valve.

The control means indicated in Fig. 1 consists of two portions, namely the idling portion A and the high speed portion B. The portion A serves to control the pump at idle or with the throttle open only a small amount. As the throttle is opened, however, portion A of the control means. becomes inactive and portion B: takes over control.

Portion A is the subject of this invention, the construction and operation of portion B being described and claimed in copending application Serial No. 370,593, dated July 27, 1953, and entitled, Fuel Injection Contro The control means of portion A is shown in Figs. 2 through 5. In these figures, a housing member or casing 17 is shown as provided with a stepped bore, in one end of which is a plug 30 containing a well for a spring 31. The center portion of the bore constitutes a chamber 32 and just above the chamber is a short sleeve 33 serving as a cylinder within which is slidably mounted the check valve fixture 14A maintained in its upper closed position by the spring 31.

The valve fixture 14A, as. shown in Fig. 5, consists of a hollow piston 34 having an enlarged head 34A piloted in the spring 31 and with radial openings 34B sufficiently distant from the head 34A to provide room for a gasket 34C which, in the upper closed position, abuts, the.

lower edge of sleeve 33 for sealing. The upper end of the bore is a part of the conduit 14.

Leading laterally from the chamber 32 is a passage 143 Opening into the lower end of dead end bore 36, in which is mounted the venturi fixture designated as 18 in Fig. 1. This venturi fixture comprises an axially drilled plug 36A, the axial passage being conical to provide the inlet end 36B of the venturi fixture. At its upper end the plug 36A is suitably formed to provide the upper end of the passage with a sharp surrounding edge. Also mounted in the bore 36, and suitably spaced from the plug MA, is a second axially drilled plug 37, the passage in this being also conical to provide the outlet end 37A of the venturi fixture. The space between the plugs 36A and 37 constitutes a low pressure throat 38.

Leading from the throat chamber 38 are a passage 14D and a conduit 20, the passage 14]) opening into the passage 14B and being controlled by the adjusting needle valve 19. The conduit 20 leads to the pump control chamber 13C.

With the throttle in closed or idle position, atmospheric pressure will prevail in conduit 14, a pressure substantially less than atmospheric in the conduit 15 and a pressure only a little below atmospheric in conduit 16. Under such conditions, there will be a considerable flow of air into conduit 14 when the engine is operating due to the differential in pressures between inlet 11 and outlet 12. The tension of spring 31 in the check valve fixture 14A will be such as to allow this valve to open easily.

This flow of air is largely through the passage 14B and through the venturi fixture 18 and is regulable by means of valve 19 controlling the bypass 14D. The more air allowed to flow through bypass 14D, the less air will flow through venturi fixture 18. With subatmospheric pressure at 12, assuming there is no venturi action, normal low pressure in the conduits 16 and 20 would exert an effect on that in the compartment 13C and thus eifect the operation of the fuel pump. The effect, however, is insufficient for desired fuel rate reduction. The venturi action therefore provides a greater reduction in pressure in compartment 13C and the fuel delivery from pump 13 is consequently reduced to achieve the fuel-air ratio required.

It should be noted that the conduit 14 is in such a position relative to throttle 17, that when throttle 17 is opened a predetermined amount, the lip of the throttle moves to a position such that the location of conduit 14 is in eifect downstream from the throttle so that the pressure in conduit 14 drops sufficiently to decrease flow through conduit 14 until it becomes insuflicient to hold open the check valve 14A. As this point is reached, and air flow through check valve 14A is stopped, the venturi action, of course, ceases. With the cessation of such action, the control of the pump is then taken over by the portion B as described in copending application aforementioned.

I claim:

1. In an apparatus for supplying fuel to an internal combustion engine having an air intake system, a throttle valve in said system and adjustable to regulate air flow through said system, and a variable delivery engine driven fuel injection pump provided with a pressure compartment and with a pressure-responsive control device in said compartment and operable to vary the fuel output of said injection pump, a control means for controlling the pressure in the pressure compartment of said pump during engine idling operation, having a first conduit connected with said air intake close to and slightly upstream of the closure point of said throttle valve such that when said throttle is open a predetermined amount, the conduit connection is essentially downstream of said throttle valve, a second conduit connected with said air intake downstream of said throttle valve such that normal pressure existing in said second conduit during engine idle operation is less than the pressure existing in said first conduit by reason of the suction effect of said engine on said air intake system downstream of said throttle valve, a valve assembly disposed between said first and second conduits, and a third conduit connecting said valve assembly with the pressure compartment of said pump, said valve assembly comprising a casing, said casing provided with a pair of chambers and a main passage connecting said chamber, a spring-closed check valve fixture supported in one of said chambers and having an intake port open to said first conduit and outlet port means disposed to open against spring tension into communication with said main passage, a venturi fixture supported in the other of said chambers, and having an inlet port in open communication with said main passage, an outlet port open to said second conduit, and a low-pressure throat intermediate said inlet and outlet ports of said venturi fixture and in open communication with said third conduit, said casing having a bypass passage connecting said main passage with said low-pressure throat of said venturi and in open communication with said third conduit, a bypass valve supported in said valve casing to adjustably open or close said bypass passage and thereby regulate the flow of air through said main passage in inverse relationship to the amount of air flow through said bypass passage, said check valve fixture opening in response to air flow through said first conduit when said throttle valve is closed to idle position sufficiently to position the connection to said air intake system of said first conduit essentially upstream of said throttle valve, said air fiow passing through said check valve fixture, said main passage, and said venturi fixture into said second conduit to further reduce the pressure in said pressure compartment of the pump by reason of the low pressure produced in the venturi lowpressure throat aforesaid, whereby to attain the fuel and air ratio required for efiicient engine idling operation.

2. In an apparatus for supplying fuel to a internal combustion engine having an air intake system, a throttle valve in said system and adjustable to regulate air flow through said system, and a variable delivery engine driven fuel injection pump, provided with a pressure compartment and with a pressure-responsive control device in said compartment and operable to vary the fuel output of said injection pump, a control means for controlling the pressure in the pressure compartment of said pump during engine idling operation, having a first conduit connected with said air intake close to and slightly upstream of the closure point of said throttle valve such that when said throttle is open a predetermined amount the conduit connection is essentially downstream of said throttle valve, a second conduit connected with said air intake throttle valve such that normal pressure existing in said second conduit during engine idle operation is less than the pressure existing in said first conduit by reason of the suction effect of said engine on said air intake system downstream of said throttle valve, a valve assembly disposed between said first and second conduits, and a third conduit connecting said valve assembly with the pressure compartment of said pump, said valve assembly comprising a check valve fixture and a venturi fixture, means urging said check valve fixture closed, passage in said valve assembly interposed said check valve fixture and said venturi valve fixture, said venturi fixture having a low-pressure throat, said low-pressure throat being constructed and arranged in open communication with said third conduit, said check valve fixture opening in response to air flow from said first conduit connected thereto, said air flow then passing through said passages and through said venturi to reduce pressure in said lowpressure throat of said venturi and in said third conduit, thereby causing a further decrease in pressure in said pressure compartment of said pump, whereby to attain the fuel and air ratio required for eflicient engine idling operation.

3. In an apparatus for supplying fuel to an internal combustion engine having an air intake system, a throttle valve in said system and adjustable to regulate air flow through said system, and a variable delivery engine driven fuel injection pump, provided with a pressure compartment and with a pressure-responsive control device in said compartment and operable to vary the fuel output of said injection pump, a control means for controlling the pressure in the pressure compartment of said pump during engine idling operation, having a first conduit connected with said air intake close to and slightly upstream of the closure point of said throttle valve such that when said throttle is open a predetermined amount the conduit connection is essentially downstream of said throttle valve, a second conduit connected with said air intake downstream of said throttle valve, such that normal pressure existing in said second conduit during the engine idle operation is less than the pressure existing in said first conduit by reason of the suction effect of said engine on said air intake system downstream of said throttle valve, a valve assembly disposed between said first and second conduits, and a third conduit connecting said valve assembly with the pressure compartment of said pump, said valve assembly comprising a check valve fixture and a venturi fixture, means urging said check valve fixture closed, passages in said valve assembly interposed in said check valve fixture and said venturi fixture, said venturi fixture having a low-pressure throat, said low-pressure throat being constructed and arranged in open communication with said third conduit, said check valve fixture opening in response to an air flow from said first conduit connected thereto, said air flow then passing through said passages and through said venturi to reduce pressure in said low-pressure throat of said venturi, and in said third conduit, thereby causing a further decrease in pressure in said pressure compartment of said pump, whereby to attain the fuel and air ratio required for efiicient engine idling operation, and adjustable means regulating the amount of air flow from said check valve fixture to said venturi fixture to modify the effect of the operation of said venturi fixture on the pressure compartment of said pump.

4. In an apparatus for supplying fuel to an internal combustion engine having an air intake system, a throttle valve in said system and adjustable to regulate air flow through said system, and a variable delivery engine driven fuel injection pump, provided with a pressure compartment and with a pressure-responsive control device in said compartment and operable to vary the fuel output of said injection pump, a control means for controlling the pressure in the pressure compartment of said pump during engine idling operation, having a first conduit connected with said air intake close to and slightly upstream of the closure point of said throttle valve such that when said throttle is open a predetermined amount the conduit connection is essentially downstream of said throttle valve, a second conduit connected with said air intake downstream of said throttle valve such that normal pressure existing in said second conduit during the engine idle operation is less than the pressure existing in said first conduit by reason of the suction eifect of said engine on said air intake system downstream of said throttle valve, a valve assembly disposed between said first and second conduits, and a third conduit connecting said valve assembly with the pressure compartment of said pump, said valve assembly comprising a check valve fixture and a venturi fixture, means urging said check valve fixture closed, passages in said valve assembly interposed to said check valve fixture and said venturi fixture, said venturi fixture having a low pressure throat, said low-pressure throat being constructed and arranged in open communication with said third conduit, said check valve fixture opening in response to an air flow from said first conduit connected thereto, said air flow then passing through said passages and through said venturi to reduce pressure in said low-pressure throat of said venturi, and in said third conduit, thereby causing a further decrease in pressure in said pressure compartment of said pump, whereby to attain the fuel and air ratio required for efiicient engine idling operation, and adjustable means regulating the amount of air flow from said check valve fixture to said venturi fixture to modify the effect of the operation of said venturi fixture on the pressure compartment of said pump, said check valve fixture adapted to close when said throttle valve is opened a predetermined amount to position the connection of said first conduit essentially downstream of said throttle valve to eliminate the air flow in said first conduit, and inactivate said venturi operation.

5. A means for controlling fuel air ratio of a fuel injection engine having an air intake system, a throttle valve associated therewith, and a variable fuel injection pump, regulable means varying the fuel injection pump output, pressure responsive means connected with said regulable means, a conduit means connecting said pressure responsive means to said air intake system downstream of said throttle valve whereby said pump is operable in response to pressures in said intake system downstream of said throttle valve for engine idling operation, said controlling means comprising a duct having a venturi and bypassing air around the throttle valve only during closed throttle operation from a point upstream of said throttle valve, through said venturi, and into said conduit means, whereby to further decrease the air pressure in said connecting means.

6. A means for controlling fuel air ratio of a fuel injection engine having an air intake system, a throttle valve associated therewith, and a variable fuel injection pump, regulable means varying the fuel injection pump output, pressure responsive means connected with said regulable means, a conduit means connecting said pressure responsive means to said air intake system downstream of said throttle valve whereby said pump is operable in response to pressures in said intake system downstream of said throttle valve for engine idling operation, said controlling means comprising a duct having a venturi and bypassing air around the throttle valve only during closed throttle operation from a point upstream of said throttle valve, through said venturi, and into said conduit means, whereby to further decrease the air pressure in said connecting means, and a second means operable for controlling pressures in the aforesaid conduit means only during engine operation at other than closed throttle operation.

References Cited in the file of this patent UNITED STATES PATENTS 2,093,984 Schweizer Sept. 21, 1937 2,341,257 Wunsch Feb. 8, 1944 2,384,282 Chandler Sept. 4, 1945 FOREIGN PATENTS 570,923 Great Britain July 30, 1945 576,886 Great Britain Apr. 25, 1946 

